Energy Harvesting Technology and Applications Team 2 AFRL WSN Health Diagnostic Energy Harvesting Technology and Applications

Introduction What is energy harvesting? Why use energy harvesting? The process by which energy is derived from external sources Why use energy harvesting? Renewable source Allows for remote charging in applications

Energy Harvesting Background Energy harvesters provide a very small amount of power for low-energy electronics The energy source for energy harvesters is present as ambient background and is free As opposed to large-scale energy generation which costs money

Why Use Energy Harvesting Technology? Converted energy can be stored in a capacitor for short-term use or a battery for long-term use. Allows for the battery (or a charger) to be taken out of the equation of an application since it sources energy from the environment

Ways to Harvest Energy Materials Other Piezoelectric Pyroelectric Photovolatics Other Kinetic Energy RF Energy

Piezoelectric Effect (Pressure) Converts mechanical strain to electric current Produces power on the order of mW Useful for small applications Handheld devices Light bulbs Human Motion Acoustic Noise Vibrations Pressure

Pyroelectric Effect Converts changes in temperatures to electric current Stable for temperatures above 1200 ⁰C High thermodynamic efficiency Used in Power Plants Automobiles Pyroelectricity (from the Greek pyr, fire, and electricity) is the ability of certain materials to generate a temporaryvoltage when they are heated or cooled.[1] The change in temperature modifies the positions of the atoms slightly within the crystal structure, such that the polarization of the material changes

Other Kinetic Energy Converts human and/or natural motion into electric current Found in Wind Turbines Ocean Wave Buoys Human Motion

Photovoltaic Effect Also known as solar power Converts solar radiation into DC Found just about everywhere and gaining more popularity

RF Energy Harvesting Converts RF signal energy into DC power RF energy is available in a wide array of frequency bands due to everyday technologies Cell Phones Radio Towers WiFi Routers Laptops TV Signals Only a tiny amount of power can be harvested, good for low power applications (Ex: A WiFi router can transmit 50-100mW) Usually very short distance, however Powercast demonstrated energy harvesting at 1.5 miles

Energy Harvesting and Wireless Sensor Networks Our project uses RF power harvesting technologies

Why RF Energy Harvesting? Ultra-low power, battery free applications Perfect for wireless sensor networks

RF Power Sources Intentional Sources Anticipated Ambient Sources Powercast utilizes a direct RF energy source, dedicated to providing RF energy for harvesting Anticipated Ambient Sources Routers, cell phone transmitters Unknown Ambient Sources Microwave radio links, mobile radios

A Closer Look at a Powercast Sensor Node Module Components & Features Powercast P2110 Powerharvester™ Receiver MCU: Microchip PIC24 XLP Radio module Microchip MRF24 (802.15.4) RF Powerharvester System power: 3.3V Capacitor 50mF (as low as 3300uF) Discrete sensors: Temp, Humidity, Light Wireless protocol: MiWi™ P2P

Sensor Module System Voltage http://powercastco.com/PDF/Design-Considerations-for-RF-Energy-Harvesting-Devices.pdf

Powercaster Transmitter Center Frequency = 915MHz Intentional RF Source Directional Antenna

Complete RF Energy Transmission

P2110 Powerharvester Receiver Efficiency

Packet Frequency vs. Distance from RF Source

Powercast Sensor Performance Overview Optimized RF Powerharvesting for the transmitter frequency RF Powerharvesting allows for remote placement of sensor nodes Great performance due to a design that focuses on minimizing power consumption in each node Proprietary wireless protocol

Conclusion Power harvesting technologies are everywhere and efficiencies are vastly improving Simply look at solar efficiencies Most of the world’s energy in the future will be generated using power harvesting technologies